The cool beans about shammies is that they have both a 1) melee dps spec, 2) ranged dps spec, 3) healing spec. So when dual-spec comes out you can go nuts with the combinations. Pallies work great with shammies because they can 1) melee dps spec, 2) tank spec, 3) healing spec -- so you can do things like...

* pally tank, 4 ele dps
* pally healer, 4 ele dps
* pally tank, 3 ele dps, 1 resto
* pally tank, 1 enh dps, 2 ele dps, 1 resto
* pally tank, 2 enh dps, 1 ele dps, 1 resto
* pally tank, 2 enh dps, 2 ele dps
* pally healer, 2 enh dps, 2 ele dps
* pally tank, 4 enh dps
* pally tank, 3 enh dps, 1 resto
* pally healer, 4 enh dps (crazy amirite?)

I would say the only more flexible class setup is potentially 5 druids (ranged dps, melee dps, tanking, healing).


P.S. "Cloth" and "Leather" are listed under the "Skills" tab for shaman. If they didn't want shaman to ever wear those items, it wouldn't be available to them. There are many cases where cloth items are more desirable than mail. There are many more cases (consider that boomkins and ele shammies -- at least at 70 -- desire similar stats) where leather > mail. On my Sunwell raiding enhancement shaman, I would've given up twice as much DKP to get my hands on the leather helm from Illidan (sadly, I lost to a higher-DKP fury warrior -- yes, a plate wearer using leather).

I've seen mages and pallies rolling on +spirit gear because, even if you ignore the spirit entirely, it's an upgrade.